Interlaced magnetic recording super parity

ABSTRACT

A storage device includes a storage medium having a first set of non-adjacent data tracks having a number of super parity sectors and a second set of non-adjacent data tracks interlaced with the first set of non-adjacent data tracks. The number of super parity sectors on a data track of the first set of non-adjacent data tracks is selected based on a distance between the data track and an inner diameter of the storage medium.

CROSS-REFERENCE TO RELATED APPLICATIONS

The present application claims benefit of priority to U.S. ProvisionalApplication No. 62/083,696, entitled “Interlaced Magnetic Recording inHAMR Devices” and filed on Nov. 24, 2014, and also to U.S. ProvisionalPatent Application No. 62/083,732, entitled “Interlaced MagneticRecording” and filed on Nov. 24, 2014. All of these applications arespecifically incorporated by reference for all that they disclose orteach.

BACKGROUND

Interlaced magnetic recording (IMR) generally refers to the concept ofutilizing two or more selected written track widths and two or moredifferent linear densities for data writes to alternating data tracks ona storage medium. In these systems, data tracks may be read from orwritten to the data tracks in a non-consecutive order. For example, datamay be written exclusively to a first track series including every otherdata track in a region of a storage medium before data is written to anydata tracks interlaced between the tracks of the first series.

SUMMARY

In IMR and similar systems, super parity sectors may be written on datatracks. These super parity sectors hold coding redundancies that enableerror correction when reading from the data track. In IMR systems, afirst set of data tracks may be written before a second set ofinterlaced data tracks are written. A data track of the first set ofdata tracks is referred to as a “bottom track,” and a data track of thesecond set of the data tracks is referred to as a “top track.” Tore-write a bottom track, two adjacent top tracks may have to be readinto memory before the bottom track is re-written. After the bottomtrack is re-written, the two adjacent top tracks are written again. Awrite of a top track can sometimes degrade the data on an adjacentbottom track (referred to as a servo write off track), but the servowrite off track may not affect the data of an adjacent top track.Because two adjacent top tracks may have to be read into memory before are-write of a bottom track and adjacent top tracks are not affected by aservo write off track, the top tracks need not include super paritysectors for error correction.

According to one implementation, a storage device includes storage mediaincluding a plurality of data tracks. The plurality of data tracksincludes one subset of bottom tracks that include one or more superparity sectors. The plurality of data tracks includes a subset of toptracks interlaced with the subset of bottom tracks, and the top tracksneed not include super parity sectors, freeing up available space foradditional data sectors, which store user data.

According to another implementation, the disclosed technology providesfor a method for writing a subset of bottom tracks including superparity sectors and subset of top tracks interlaced with the subset ofbottom tracks, wherein the subset of top tracks need not include superparity sectors, freeing up available space for additional data sectors.

According to yet another implementation, a storage device includesstorage media including a plurality of data tracks. The plurality ofdata tracks includes one subset of bottom tracks having one or moresuper parity sectors. The number one or more super parity sectors isselecting according to a distance of the plurality of data tracks froman inner diameter of the storage media.

This Summary is provided to introduce a selection of concepts in asimplified form that are further described below in the DetailedDescription. This Summary is not intended to identify key features oressential features of the claimed subject matter, nor is it intended tobe used to limit the scope of the claimed subject matter. These andvarious other features and advantages will be apparent from a reading ofthe following Detailed Description.

BRIEF DESCRIPTIONS OF THE DRAWINGS

FIG. 1 illustrates a plan view of an example disc drive assembly.

FIG. 2 illustrates example data writes to a magnetic disc in aninterlaced magnetic recording (IMR) system.

FIG. 3 illustrates another example of data writes to a magnetic disc inan IMR system.

FIG. 4 illustrates yet another example of data writes to a magnetic discin an IMR system.

FIG. 5 illustrates an example storage media system.

FIG. 6 illustrates example operations for writing to a magnetic disc inan IMR system.

FIG. 7 illustrates an example schematic of storage controller of a discdrive assembly.

DETAILED DESCRIPTION

As requirements for area storage density increase for magnetic media,cell size decreases. A commensurate decrease in the size of a writeelement is difficult because in many systems, a strong write field isneeded to shift the polarity of cells on a magnetized medium. As aresult, writing data to smaller cells on the magnetized medium using therelatively larger write pole may affect the polarization of adjacentcells (e.g., overwriting the adjacent cells). One technique for adaptingthe magnetic medium to utilize smaller cells while preventing adjacentdata from being overwritten during a write operation is interlacedmagnetic recording (IMR).

As explained in further detail with reference to the various figuresbelow, IMR systems may utilize two or more selected written track widthsand two or more different linear densities for data writes toalternating data tracks on a storage medium. In these systems, datatracks may be read from or written to the data tracks in anon-consecutive order. For example, data may be written exclusively to afirst track series including every other data track in a region of astorage medium before data is written to any data tracks interlacedbetween the tracks of the first series.

In IMR systems, a data track of wide written track width is writtenprior to directly adjacent data tracks of narrower written track width.The data tracks of the wider written track width are also referred toherein as “bottom tracks,” while the alternating data tracks of narrowerwritten width are referred to herein as “top tracks.”

In some implementations, the bottom tracks of wider written track widthinclude data stored at a different linear density than one or more toptracks of narrow written track width. In still other implementations(e.g., on a bit-patterned media), the bottom and top data tracks are ofequal written track width.

IMR can allow for significantly higher areal recording densities thanmany existing data management systems. However, effective IMR systemsare designed to implement prioritized write access rules that can, insome implementations, entail significant read/write overhead. Forinstance, modifying a target data track in an IMR system may entailreading two or more adjacent top tracks into memory, modifying thetarget bottom track, and re-writing the two or more adjacent top tracks.The herein-disclosed technology explores the convergence of IMR withsuper parity sectors to increase user data area in IMR systems. Superparity sectors are included in a data track and are encoded with codingredundancies through error correction code (ECC) to enable errorcorrection for the data track. Because of the prioritized access rulesemployed by IMR, top tracks may not need super parity sectors to correcterrors.

FIG. 1 illustrates a plan view of an example disc drive assembly 100.Disc drive assembly includes a transducer head assembly 120 with awriter and reader (not shown) for writing and reading data to and from amagnetic storage medium 108. Transducer head assembly may include anumber of reader and writer configurations such as HAMR, multiple readand/or write heads, etc. Although other implementations arecontemplated, the magnetic storage medium 108 is, in FIG. 1, a magneticstorage disc on which data bits can be recorded using a magnetic writepole and from which data bits can be read using a magnetoresistiveelement (not shown). As illustrated in View A, the magnetic storagemedium 108 rotates about a spindle center or a disc axis of rotation 112during rotation, and includes an inner diameter 104 and an outerdiameter 102 between which are a number of concentric data tracks 110.Information may be written to and read from data bit locations in thedata tracks on the magnetic storage medium 108.

The magnetic storage medium 108 is includes a number of servo sectors(e.g., a servo sector 112) extending radially between the inter diameter104 and the outer diameter 102. In one implementation, each of the servosectors (e.g., servo sector 112) includes embedded information used fortrack seeking and track following. In particular, the informationincludes fine head position information used for centerline trackingBetween every two consecutive servo sectors (e.g., servo sector 112) isa wedge (e.g., a wedge 114) that includes multiple sectors (e.g., datasectors and super parity sectors, not shown) of concentric data tracks110.

The transducer head assembly 120 is mounted on an actuator assembly 109at an end distal to an actuator axis of rotation 114. The transducerhead assembly 120 flies in close proximity above the surface of themagnetic storage medium 108 during disc rotation. The actuator assembly109 rotates during a seek operation about the actuator axis of rotation112. The seek operation positions the transducer head assembly 120 overa target data track for read and write operations.

The storage device 100 further includes a storage controller 106. Thestorage controller 106 includes software and/or hardware, and may beimplemented in any tangible processor-readable storage media within orcommunicatively coupled to the storage device 100. The term “tangibleprocessor-readable storage media” includes, but is not limited to, RAM,ROM EEPROM, flash memory or other memory technology, CDROM, digitalversatile disks (DVD) or other optical disk storage, magnetic cassettes,magnetic tape, magnetic disk storage or other magnetic storage devices,or any other tangible medium which can be used to store the desiredinformation and which can be accessed by a processor. In contrast totangible processor-readable storage media, intangible processor readablecommunication signals may embody processor readable instructions, datastructures, program modules or other data resident in a modulated datasignal, such as a carrier wave or other signal transport mechanism. Theterm “modulated data signal” means a signal that has one or more of itscharacteristics set or changed in such a manner as to encode informationin the signal.

View B illustrates a magnified view of a section of the magnetic storagemedium 108 including data tracks (e.g., data tracks 130, 131, and 132)storing data according to an interlaced magnetic recording (IMR)technique. The data tracks (e.g., data tracks 130, 131, and 132) aredivided in to data sectors (e.g., data sectors 182, 180, and 184) whichinclude a plurality of polarized regions (not shown), also referred toas “data bits,” each representing one or more individual data bits ofthe same state (e.g., 1s or 0s). One or more of the data sectors of eachdata track may be reserved as a super parity sector for that data track(e.g., a super parity sector 170 for the data track 131 and a superparity sector 172 for the data track 133). The super parity sectors areencoded with coding redundancies through error correction code (ECC) toenable error correction for the data track.

The illustrated IMR technique utilizes alternating data tracks ofdifferent written track widths arranged with slightly overlappingwritten track boundaries so that a center-to-center distance betweendirectly adjacent tracks (e.g., the track pitch) is uniform across anarea (e.g., a radial zone or across an entire surface of the magneticstorage medium 108). Specifically, View B illustrates a first series ofalternating tracks (e.g., the tracks 131 and 133) with a wider writtentrack width than a second series of alternating data tracks (e.g., thetracks 130, 132, and 134). The first series of alternating tracks arebottom tracks, and the second series of alternating tracks are toptracks.

According to one implementation, each wide data track (i.e., bottomtrack) of the first series is written before the data is written to anydirectly-adjacent data tracks (i.e., top tracks) of the second series.For example, the data track 131 is written before data is written toeither of the data tracks 130 and 132. Data writes to the data tracks130 and 132 may subsequently overwrite outer edge portions of the datatrack 131; however, the data track 131 is still readable due tosufficient information retained in a center region of the data track131.

One consequence of IMR is that a bottom track (e.g., a data track 131)is not randomly writable when data is stored on a directly adjacent topdata track (e.g., the data track 130 or 132). As used herein, a datatrack is “randomly writable” when the data track can be individuallyre-written multiple times without significantly degrading data on otheradjacent data tracks. An adjacent data track is “significantly degraded”if reading the data track results in a number of read errors in excessof a maximum number of errors that can be corrected by a correction code(ECC) of the data storage device 100. Top tracks (e.g., data tracks 130,132, and 134) are generally randomly writable because they can beindividually rewritten without degrading data on other adjacent datatracks. However, some implementations of IMR systems have issues withservo write off track (SWOT), meaning that the write head of thetransducer head 120 writes off center of the target track and into anadjacent track resulting in a degradation of the data on the adjacenttrack. For example, if transducer head 120 is writing on top track 132it may write off center of the top track 132 (e.g., toward the bottomtrack 131), which may degrade the data on the bottom track 131. When thetransducer head 120 suffers from SWOT such as in the example describedabove, it may not have an effect on the opposing top track (e.g., thetop track 130). Only the adjacent bottom track 131 may be affected.

In some implementations, top tracks (e.g., top track 130) may includeone or more super parity sectors to account for storage media failuremodes other than a SWOT, such as grown defect. However, because a SWOTwhen writing a top track generally affects only adjacent bottom tracksand may not affect adjacent top tracks, top tracks may not include superparity sectors to account for a SWOT. Bottom tracks may need to includeone or more super parity sectors to account for SWOT. Therefore, thenumber of super parity sectors on a top track may generally be less thanthe number of super parity sectors on bottom tracks. Thus, additionalspace for user data is available on top tracks.

In typical IMR systems, both bottom tracks (e.g., the bottom track 131)and top tracks (e.g., the top track 130) include super parity sectorsfor error correction. However, because the data of the bottom tracks(e.g., bottom track 131 or 133) may be affected during SWOT of a toptrack (e.g., the top track 132), it may be necessary to include superparity sectors (e.g., the super parity sector 170 on the bottom track131 and the super parity sector 172 on the bottom track 133) to enableerror correction for each bottom track. Because the top tracks (e.g.,top tracks 130,132, and 134) are randomly writeable and any adjacent toptrack is generally read (e.g., top tracks 130 and 132) before a bottomtrack (e.g., 131) can be re-written, it may not be necessary to includea super parity sector on any top track. Because super parity sectors maynot be included to correct errors on top tracks, the space can be usedfor additional user data.

A sector based ECC encoder adds coding redundancies to a data stream toenable error correction within an area of a storage medium. When data isread back from the area of the storage medium, ECC coding redundanciesstored in the super parity sectors are used to help insure that the datais read back correctly. A sector-based ECC as described herein may beused to correct data from a number of data sectors by analyzing dataread from the number of sectors.

The error-correcting capability of an encoder or multiple encoders is,in some implementations, limited by the number of parity sectors holdingthe redundancies that the encoders add to the data stream. In theory,the larger the number of parity sectors associated with a data track,the larger number of errors that can be corrected in the data when it isread back. However, as more super parity sectors are added to the datastream, more space is delegated to these super parity sectors at theexpense of data sectors. Thus tradeoffs between storage space and errorcorrection power exist.

The above-described IMR data management techniques can be used toincrease storage media area for user data. Storage area gains for IMRsystems are described further with respect to the following figures.

FIG. 2 illustrates example data writes 200 to a magnetic disc in aninterlaced magnetic recording (IMR) system. A controller (not shown) ofthe IMR system implements a write management scheme to ensure thatgroupings of adjacent data tracks are written in an order such that dataof almost all tracks are readable and a total read/write processing timeis mitigated. The prioritized write access scheme may govern data writesto an entire magnetic disc, or (alternatively) govern data writes to asubset of a magnetic disc, such as a radial zone or partitioned storagearea of the magnetic disc.

According to one implementation, the write management scheme includesmultiple phases, with different write prioritization rules appliedduring each distinct phase. In a first phase of the write managementscheme, data is written exclusively to bottom tracks. In someimplementations consecutive bottom tracks (e.g., bottom tracks 203, 205,207, 209) are written to in a consecutive order as illustrated by thenotation “Write 1,” “Write 2,” “Write, 3” and “Write 4.” However, otherimplementations are contemplated. For example, bottom tracks (e.g.,bottom tracks 203, 205, 207, and 209) may be written non-sequentially,such as writing every other bottom track or writing in some other order.During this first phase, the bottom tracks are divided into sectors andsome sectors are reserved as data sectors (e.g., data sectors 213, 215,217, and 219) and other sectors are reserved as super parity sectors(e.g., super parity sector 223, 225, 227, and 229). The data sectorshold user data; in contrast, the super parity sectors are encoded withredundancies by error correction code (ECC). For example, super paritysector 223 will be encoded with redundancies to correct error in readsfrom bottom track 203, and super parity sector 225 will be encoded withredundancies to correct errors in reads from bottom track 205.

The first phase of writing bottom tracks with data sectors and superparity sectors continue until a first capacity condition is satisfied.For example, the first capacity condition may be satisfied when 50% ofthe data tracks in a region (i.e., a specific radial or zone or theentire disc surface) store data. During this first phase of the datamanagement method, each of the bottom data tracks (e.g., bottom tracks203, 205, 207, and 209) can be written to at random and directlyoverwritten without re-writing data of adjacent data tracks.

After the first capacity condition is satisfied, a second phase of thewrite management scheme commences and the controller begins to directnew incoming data to the top data tracks (not shown). In someimplementations, consecutive top data tracks are written to in aconsecutive order as illustrated by the notation “Write 5,” “Write 6,”and “Write 7.” However, other implementations are contemplated. Forexample, top tracks may be written non-sequentially such as every othertop track. By writing to alternating top data tracks (e.g., “Write 5”then “Write 7”), the storage device can avoid reading/re-writing morethan two data tracks in a single track write for a period of time as thestorage media fills up. In IMR implementations, the top tracks aredivided into sectors, and some sectors are reserved as super paritysectors. In this example implementation, the top tracks are divided intosectors, but no sectors are reserved as super parity sectors. Superparity sectors may not be required for the top tracks because they arerandomly writeable and generally must be read into memory to rewrite anyadjacent bottom sector. This scheme results in more user data sectorsand is explained further with respect to FIGS. 3 and 4.

FIG. 3 illustrates another example of data writes 300 to a magnetic discin an IMR system. A controller (not shown) of the IMR system implementsa write management scheme to ensure that groupings of adjacent datatracks are written in an order such that data of almost all tracks arereadable and a total read/write processing time is mitigated. Theprioritized write access 'scheme may govern data writes to an entiremagnetic disc, or (alternatively) govern data writes to a subset of amagnetic disc, such as a radial zone or partitioned storage area of themagnetic disc.

According to one implementation, the write management scheme includesmultiple phases, with different write prioritization rules appliedduring each distinct phase. In a first phase of the write managementscheme, data is written exclusively to bottom tracks. In someimplementations consecutive bottom tracks (e.g., bottom tracks 303, 305,307, 309) are written to in a consecutive order as illustrated by thenotation “Write 1,” “Write 2,” “Write, 3” and “Write 4.” However, otherimplementations are contemplated. For example, bottom tracks (e.g.,bottom tracks 303, 305, 307, and 309) may be written non-sequentiallysuch as every other bottom track. During this first phase, the bottomtracks are divided into sectors and some sectors are reserved as datasectors (e.g., data sectors 313, 315, 317, and 319) and other sectorsare reserved as super parity sectors (e.g., super parity sectors 323,325, 327, and 329). The data sectors hold user data; in contrast, thesuper parity sectors are encoded with redundancies by error correctioncode (ECC). For example, the super parity sector 323 will be encodedwith redundancies to correct error in reads from the bottom track 303,and the super parity sector 325 will be encoded with redundancies tocorrect errors in reads from the bottom track 305.

The first phase of writing bottom tracks with data sectors and superparity sectors continue until a first capacity condition is satisfied.For example, the first capacity condition may be satisfied when 50% ofthe data tracks in a region (i.e., a specific radial or zone or theentire disc surface) store data. During this first phase of the datamanagement method, each of the bottom data tracks (e.g., bottom tracks303, 305, 307, and 309) can be written to at random and directlyoverwritten without re-writing data of adjacent data tracks.

After the first capacity condition is satisfied, a second phase of thewrite management scheme commences and the controller begins to directnew incoming data to the top data tracks (e.g., the top track 304). Insome implementations, consecutive top data tracks are written to in aconsecutive order as illustrated by the notation “Write 5,” “Write 6,”and “Write 7.” However, other implementations are contemplated. Forexample, top tracks may be written non-sequentially such as every othertop track. By writing to alternating top data tracks (e.g., “Write 5”then “Write 7”), the storage device can avoid reading/re-writing morethan two data tracks in a single track write for a period of time as thestorage media fills up.

Top tracks are generally randomly writeable and generally must be readinto memory to rewrite any adjacent bottom track. For example,over-writing bottom track 303 during the second phase of the writemanagement scheme entails (1) reading the top track 304 to a temporarycache location; (2) writing the bottom track 303; and (3) re-writing thetop track 304 after the write of the bottom track 303 is complete.

Further, during the second phase of the write management scheme, thebottom tracks (e.g., bottom tracks 303 and 305) may be affected by servowrite off track (SWOT), which is the result of a transducer head (notshown) being off-center of a target top track (e.g., the top track 304)while writing. A SWOT can degrade the data on an adjacent bottom track(e.g., the bottom track 305). However, a SWOT generally does not affectan adjacent top track (e.g., a data track located in an area 306 betweenthe bottom tracks 305 and 307). Because top tracks are generallyrandomly writeable and the data of top tracks may not be affected by aSWOT, super parity sectors are not needed to correct the data of toptracks when the top tracks are read. The space reserved for paritysectors can now be used for user data (e.g., data sectors 314),resulting in more user data space across the entire storage medium.

FIG. 4 illustrates another example of data writes 400 to a magnetic discin an IMR system. A controller (not shown) of the IMR system implementsa write management scheme to ensure that groupings of adjacent datatracks are written in an order such that data of almost all tracks arereadable and a total read/write processing time is mitigated. Theprioritized write access scheme may govern data writes to an entiremagnetic disc, or (alternatively) govern data writes to a subset of amagnetic disc, such as a radial zone or partitioned storage area of themagnetic disc.

According to one implementation, the write management scheme includesmultiple phases, with different write prioritization rules appliedduring each distinct phase. In a first phase of the write managementscheme, data is written exclusively to bottom tracks. In someimplementations consecutive bottom tracks (e.g., bottom tracks 403, 405,407, 409) are written to in a consecutive order as illustrated by thenotation “Write 1,” “Write 2,” “Write,3” and “Write 4.” However, otherimplementations are contemplated. For example, the bottom tracks (e.g.,bottom tracks 403, 405, 407, and 409) may be written non-sequentiallysuch as every other bottom track. During this first phase, the bottomtracks are divided into sectors and some sectors are reserved as datasectors (e.g., data sectors 413, 415, 417, and 419) and other sectorsare reserved as super parity sectors (e.g., super parity sectors 423,425, 427, and 429). The data sectors hold user data; in contrast, thesuper parity sectors are encoded with redundancies by error correctioncode (ECC). For example, the super parity sector 423 will be encodedwith redundancies to correct error in reads from the bottom track 403,and the super parity sector 425 will be encoded with redundancies tocorrect errors in reads from the bottom track 405.

The first phase of writing bottom tracks with data sectors and superparity sectors continue until a first capacity condition is satisfied.For example, the first capacity condition may be satisfied when 50% ofthe data tracks in a region (i.e., a specific radial or zone or theentire disc surface) store data. During this first phase of the datamanagement method, each of the bottom data tracks (e.g., bottom tracks403, 405, 407, and 409) can be written to at random and directlyoverwritten without re-writing data of adjacent data tracks.

After the first capacity condition is satisfied, a second phase of thewrite management scheme commences and the controller begins to directnew incoming data to the top data tracks (e.g., top tracks 404, 406, and408). In some implementations, consecutive top data tracks are writtento in a consecutive order as illustrated by the notation “Write 5,”“Write 6,” and “Write 7.” However, other implementations arecontemplated. For example, top tracks may be written non-sequentiallysuch as every other top track. By writing to alternating top data tracks(e.g., “Write 5” then “Write 7”), the storage device can avoidreading/re-writing more than two data tracks in a single track write fora period of time as the storage media fills up.

Top tracks are generally randomly writeable and must generally be readinto memory to rewrite any adjacent bottom track. For example,over-writing the bottom track 405 during the second phase of the writemanagement scheme entails (1) reading the top tracks 404 and 406 to atemporary cache location; (2) writing the top track 405; and (3)re-writing the top tracks 404 and 406 after the write of the bottomtrack 405 is complete.

Further, during the second phase of the write management scheme, thebottom tracks (e.g., bottom tracks 403 and 405) may be affected by servowrite off track (SWOT), which is the result of a transducer head (notshown) being off-center of a target top track (e.g., top track 404)while writing. A SWOT can degrade the data on an adjacent bottom track(e.g., bottom track 405). However, a SWOT generally does not affect anadjacent top track (e.g., e.g., top track 406). Because top tracks aregenerally randomly writeable and the data of top tracks may not beaffected by a SWOT, super parity sectors are not needed to correct thedata of top tracks when the top tracks are read. The space reserved forparity sectors can now be used for user data (e.g., data sectors 414,416, 418), resulting in more user data space across the entire storagemedium.

FIG. 5 illustrates an example data storage system 500. The storagesystem 500 includes magnetic storage media 508. Although otherimplementations are contemplated, the magnetic storage media 508 is, inFIG. 1, a magnetic storage disc on which data bits can be recorded usinga magnetic write pole and from which data bits can be read using amagnetoresistive element (not shown). The magnetic storage media 508includes a number of servo sectors (e.g., a servo sector 512) extendingradially between an inter diameter 504 and outer diameter 502. In oneimplementation, each of the servo sectors includes embedded informationused for track seeking and track following. In particular, theinformation includes fine head position information used for centerlinetracking Between every two consecutive servo sectors (e.g., servo sector512) is a wedge (e.g., a wedge 514) that includes a length of multipledata tracks (e.g., data tracks 542, 544, and 546). The data tracks aredivided into a number of sectors (e.g., sector 520). Each sector 520 iseither a data sector that holds user data or a super parity sector thatholds redundancies for error correction.

The data tracks (e.g., 542, 544, and 546) of the magnetic storage media508 may be grouped into different physical zones between the innerdiameter 504 and the outer diameter 502. For example, data track 546 maybe assigned to a zone 1; data track 544 may be assigned to a zone 2; anddata track 542 may be assigned to a zone 3. In other implementations,the media 508 may be grouped into greater than or fewer than threedifferent zones. Each of the zones of the magnetic storage media 508 mayinclude more than 1 data track.

In this example implementation, the data tracks 542, 544, and 546include one or more super parity sectors. This example implementationmay be used in systems other than IMR systems, such as PMR(perpendicular magnetic recording), SMR (shingled magnetic recording),BPM (bit patterned media), etc. In this example implementation, thenumber of parity sectors on a track is selected based on the track'sdistance from inner diameter 504 of magnetic storage media 508. Tracksthat are closer to inner diameter 504 (e.g., data track 546) have lessusable area than a track that is further from inner diameter 504 (e.g.,data track 542). Consequently, a track nearer to inner diameter 504 willhold less data than a track nearer to outer diameter 502. As a result ofthe lower amount of data, a track near the inner diameter 504 willrequire less space for holding redundancies for error corrections in oneor more super parity sectors than a track near an outer diameter, whichwill require more redundancies for the larger amount of data. Forexample, the data track 546 may include three super parity sectors datatrack 544 may include four super parity sectors; and data track 542 mayinclude five super parity sectors. In one implementation, the number ofparity sectors per track may increase proportionally with the increasein distance of each track from the inner diameter 504. However, inalternative implementation, the increase in the number of super paritysectors may be not proportional with the increase in the distance ofeach track from the inner diameter 504.

FIG. 6 illustrates example operations 600 for writing to a magnetic discin an IMR system. The operations 600 may be controlled by a storagecontroller, which includes a processor. The storage controller maycontrol the location of read and writes, and controls the inclusion ofone or more parity sectors on data tracks. The storage controller mayalso control the writing of servo sectors. A writing operation 605writes set of bottom tracks with at least one parity sector. The writingoperation 605 may be in response to a write command from the storagecontroller. The write command may include an amount of data and alocation on the magnetic disc. One or more data sectors are filled withthe amount of data and the at least one super parity sector is encodedaccording to an error correction code (ECC). The write operation 605 mayselect and write a number of super parity sectors depending on adistance between a data track of the set of bottom tracks and an innerdiameter of the magnetic disc. The write operation 605 may write thedata tracks in an order according to a prioritization rule controlled bythe storage controller. A second write operation 610 writes a set of toptracks interlaced with the set of bottom tracks. The second writeoperation 610 may be in response to a write command from the storagecontroller. The write command may include an amount of data and alocation on the magnetic disc. The second write operation 610 writesdoes not write a data sector on at least one data track of the set oftop tracks. The second write operation 610 will write the set of toptracks in an order according to a prioritization rule, controlled by thestorage controller.

FIG. 7 illustrates an example schematic 700 of a storage controller 708of a disc drive assembly. Specifically, FIG. 7 shows one or morefunctional circuits that are resident on a printed circuit board used tocontrol the operation of the disc drive. The controller 708 is operablyand communicatively connected to a host computer 702. Controlcommunication paths are provided between the host computer 702 and aprocessor 704, the processor 704 generally providing top-levelcommunication and control for the controller 708 in conjunction withprocessor readable instructions for the processor 704 encoded inprocessor readable storage media 706. The processor readableinstructions comprise instructions for controlling writing to andreading from data tracks on a storage media 710. The processor readableinstructions further include instructions for encoding parity bits onparity sectors on the data tracks of storage media, the parity sectorsproviding error correction for the storage data tracks on storage media710.

The term “processor readable storage media” includes but is not limitedto, random access memory (“RAM”), ROM, EEPROM, flash memory or othermemory technology, CDROM, digital versatile disks (DVD) or other opticaldisk storage, magnetic cassettes, magnetic tape, magnetic disk storageor other magnetic storage devices, or any other tangible medium whichcan be used to store the desired information and which can be accessedby a processor. In contrast to tangible processor-readable storagemedia, intangible processor-readable communication signals may embodyprocessor readable instructions, data structures, program modules orother data resident in a modulated data signal, such as a carrier waveor other signal transport mechanism. Note that while, the system formanagement of system files on a storage device is disclosed herein incontext of an HDD, one or more aspects the technology disclosed hereinmay also be applicable to other storage devices enumerated above.

The storage controller 708 controls storage of data on the storage media710 such as magnetic disc, optical discs, etc. A spindle motor controlcircuit 712 controls the rotation of storage media 710. A servo circuit714 provides control for moving an actuator that moves heads (not shown)between tracks on the storage media 710 and controls the position of thehead.

Other configurations of storage controller 708 are contemplated. Forexample, storage controller 708 may include on or more of an interfacecircuitry, a buffer, a disc drive platform buffer manager (PBM), aformatter, etc. The processor readable instructions may be included onthe host computer or somewhere else on a storage system.

The above specification, examples, and data provide a completedescription of the structure and use of example embodiments of thedisclosed technology. Since many embodiments of the disclosed technologycan be made without departing from the spirit and scope of the disclosedtechnology, the disclosed technology resides in the claims hereinafterappended. Furthermore, structural features of the different embodimentsmay be combined in yet another embodiment without departing from therecited claims.

What is claimed is:
 1. A storage device comprising: a storage mediaincluding a plurality of data tracks, the plurality of data tracksincluding a subset of bottom tracks and a subset of top tracks, whereinat least one bottom track of the subset of bottom tracks includes one ormore super parity sectors providing error correction for the at leastone bottom track of the subset of bottom tracks, and wherein at leastone top track of the subset of top tracks does not include one or moresuper parity sectors.
 2. The storage device of claim 1, wherein thesubset of top tracks is interlaced with the subset of bottom tracks. 3.The storage device of claim 1, wherein the subset of bottom tracks iswritten before the subset of top tracks.
 4. The storage device of claim1, further comprising a storage controller configured to control readingfrom and writing to the subset of top tracks and the subset bottomtracks in a manner that avoids data corruption.
 5. The storage device ofclaim 1, wherein a number of super parity sectors of the one or moresuper parity sectors is selected based on a distance of the at least onebottom track of the subset of bottom tracks from an inner diameter ofthe storage media.
 6. The storage device of claim 1, wherein a write ofa first data track of the subset of top tracks does not affect data ofan adjacent second data track of the subset of top tracks.
 7. A methodcomprising: writing a set of bottom tracks to a storage medium, whereinthe set of bottom tracks includes at least one parity sector; andwriting a set of top tracks to the storage medium, wherein each toptrack of the set of top tracks is interlaced with two bottom tracks ofthe set of bottom tracks, and wherein at least one top track of the setof top tracks does not include a super parity sector.
 8. The method ofclaim 7, wherein the set of bottom tracks and the set of top tracksinclude servo sectors.
 9. The method of claim 8, wherein writing a toptrack of the set of top tracks does not affect data of an adjacent trackof the set of top tracks.
 10. The method of claim 8, wherein the set ofbottom tracks are written before the set of top tracks.
 11. The methodof claim 8, further comprising: reading at least one top track of theset of top tracks into a temporary cache; over-writing an adjacentbottom track of the set of bottom tracks; and re-writing the at leastone top track after the over-writing of the adjacent bottom track iscomplete.
 12. The method of claim 7, wherein a number of parity sectorson the set of bottom tracks is selected based on a distance between abottom track of the set of bottom tracks and a diameter of the storagemedium.
 13. The method of claim 7, wherein the parity sectors provideerror correction for the set of bottom tracks.
 14. One or moreprocessor-readable storage media encoding computer-executableinstructions for executing on a computer system a computer process, thecomputer process comprising: writing a set of bottom tracks to a storagemedium, wherein the set of bottom tracks includes at least one paritysector; and writing a set of top tracks to the storage medium, whereineach top track of the set of top tracks is interlaced with two bottomtracks of the set of bottom tracks, and wherein at least one top trackof the set of top tracks does not include a super parity sector.
 15. Theone or more processor-readable storage medium of claim 14, wherein theset of bottom tracks and the set of top tracks include servo sectors.16. The one or more processor-readable storage medium of claim 15,wherein writing a top track of the set of top tracks does not affectdata of an adjacent track of the set of top tracks.
 17. The one or moreprocessor-readable storage medium of claim 15, wherein the set of bottomtracks are written before the set of top tracks.
 18. The one or moreprocessor-readable storage medium of claim 15, further comprising:reading at least one top track of the set of top tracks into a temporarycache; over-writing an adjacent bottom track of the set of bottomtracks; and re-writing the at least one top track after the over-writingof the adjacent bottom track is complete.
 19. The one or moreprocessor-readable storage medium of claim 14, wherein a number ofparity sectors on the set of bottom tracks is selected based on adistance between a bottom track of the set of bottom tracks and adiameter of the storage medium.
 20. The one or more processor-readablestorage medium of claim 14, wherein the parity sectors provide errorcorrection for the set of bottom tracks.